/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/

#include "itkWarpHarmonicEnergyCalculator.h"
#include "itkImageRegionIteratorWithIndex.h"
#include "itkMath.h"
#include "itkTestingMacros.h"


int itkWarpHarmonicEnergyCalculatorTest( int argc, char* argv[] )
{
  if( argc != 4 )
    {
      std::cerr << "Missing parameters." << std::endl;
      std::cerr << "Usage: " << argv[0]
        << " useImageSpacing"
        << " derivativeWeights"
        << " expectedEnergy" << std::endl;
      return EXIT_FAILURE;
    }

  // Define the dimension of the images
  constexpr unsigned int ImageDimension = 3;

  using DeformationPixelType = itk::Vector< double, ImageDimension >;

  // Declare the types of the images
  using DisplacementFieldType = itk::Image< DeformationPixelType, ImageDimension >;

  // Declare the type of the index to access images
  using IndexType = itk::Index< ImageDimension >;

  // Declare the type of the size
  using SizeType = itk::Size< ImageDimension >;

  // Declare the type of the region
  using RegionType = itk::ImageRegion< ImageDimension >;

  // Create the input image
  DisplacementFieldType ::Pointer inputDisplacementField =
    DisplacementFieldType ::New();

  // Define its size, and start index
  SizeType size;
  size[0] = 2;
  size[1] = 2;
  size[2] = 2;

  IndexType start;
  start[0] = 0;
  start[1] = 0;
  start[2] = 0;

  RegionType region;
  region.SetIndex( start );
  region.SetSize( size );

  // Initialize the input image
  inputDisplacementField->SetLargestPossibleRegion( region );
  inputDisplacementField->SetBufferedRegion( region );
  inputDisplacementField->SetRequestedRegion( region );
  inputDisplacementField->Allocate();

  // Initialize the content of the input image
  DeformationPixelType vectorValue;
  vectorValue.Fill( 5.0 ); // FIXME: replace with something more interesting...
  inputDisplacementField->FillBuffer( vectorValue );

  // Declare the type for the itk::WarpHarmonicEnergyCalculator
  using CalculatorType = itk::WarpHarmonicEnergyCalculator< DisplacementFieldType >;


  // Create the calculator
  CalculatorType::Pointer calculator = CalculatorType::New();

  ITK_EXERCISE_BASIC_OBJECT_METHODS( calculator, WarpHarmonicEnergyCalculator,
    Object );


  auto useImageSpacing = static_cast< bool >( std::stoi( argv[1] ) );
  ITK_TEST_SET_GET_BOOLEAN( calculator, UseImageSpacing, useImageSpacing );

  CalculatorType::WeightsType derivativeWeights;
  derivativeWeights.Fill( std::stod( argv[2] ) );
  calculator->SetDerivativeWeights(derivativeWeights );
  ITK_TEST_SET_GET_VALUE( derivativeWeights, calculator->GetDerivativeWeights() );

  // Set the input image
  calculator->SetImage( inputDisplacementField );

  // Execute the calculator
  ITK_TRY_EXPECT_NO_EXCEPTION( calculator->Compute() );

  // Regression test: check the computed harmonic energy
  double expectedEnergy = std::stod( argv[3] );
  const double computedEnergy = calculator->GetHarmonicEnergy();
  if( itk::Math::NotAlmostEquals( expectedEnergy, computedEnergy ) )
    {
    std::cerr << "Test failed!" << std::endl;
    std::cerr << "Error in GetHarmonicEnergy()" << std::endl;
    std::cerr << "Expected: " << expectedEnergy
      << ", but got: " << computedEnergy << std::endl;
    return EXIT_FAILURE;
    }


  std::cout << "Test finished." << std::endl;
  return EXIT_SUCCESS;
}
